netdev - Re: [PATCH ghak90 V8 07/16] audit: add contid support for signalling the audit daemon

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Message-ID: <CAHC9VhR2zCCE5bjH75rSwfLC7TJGFj4RBnrtcOoUiqVp9q5TaA@mail.gmail.com>
Date:   Wed, 18 Mar 2020 16:56:46 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     Richard Guy Briggs <rgb@...hat.com>
Cc:     Steve Grubb <sgrubb@...hat.com>, linux-audit@...hat.com,
        nhorman@...driver.com, linux-api@...r.kernel.org,
        containers@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>, dhowells@...hat.com,
        netfilter-devel@...r.kernel.org, ebiederm@...ssion.com,
        simo@...hat.com, netdev@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, Eric Paris <eparis@...isplace.org>,
        mpatel@...hat.com, Serge Hallyn <serge@...lyn.com>
Subject: Re: [PATCH ghak90 V8 07/16] audit: add contid support for signalling
 the audit daemon

On Fri, Mar 13, 2020 at 2:59 PM Richard Guy Briggs <rgb@...hat.com> wrote:
> On 2020-03-13 12:29, Paul Moore wrote:
> > On Thu, Mar 12, 2020 at 3:30 PM Richard Guy Briggs <rgb@...hat.com> wrote:
> > > On 2020-02-13 16:44, Paul Moore wrote:
> > > > This is a bit of a thread-hijack, and for that I apologize, but
> > > > another thought crossed my mind while thinking about this issue
> > > > further ... Once we support multiple auditd instances, including the
> > > > necessary record routing and duplication/multiple-sends (the host
> > > > always sees *everything*), we will likely need to find a way to "trim"
> > > > the audit container ID (ACID) lists we send in the records.  The
> > > > auditd instance running on the host/initns will always see everything,
> > > > so it will want the full container ACID list; however an auditd
> > > > instance running inside a container really should only see the ACIDs
> > > > of any child containers.
> > >
> > > Agreed.  This should be easy to check and limit, preventing an auditd
> > > from seeing any contid that is a parent of its own contid.
> > >
> > > > For example, imagine a system where the host has containers 1 and 2,
> > > > each running an auditd instance.  Inside container 1 there are
> > > > containers A and B.  Inside container 2 there are containers Y and Z.
> > > > If an audit event is generated in container Z, I would expect the
> > > > host's auditd to see a ACID list of "1,Z" but container 1's auditd
> > > > should only see an ACID list of "Z".  The auditd running in container
> > > > 2 should not see the record at all (that will be relatively
> > > > straightforward).  Does that make sense?  Do we have the record
> > > > formats properly designed to handle this without too much problem (I'm
> > > > not entirely sure we do)?
> > >
> > > I completely agree and I believe we have record formats that are able to
> > > handle this already.
> >
> > I'm not convinced we do.  What about the cases where we have a field
> > with a list of audit container IDs?  How do we handle that?
>
> I don't understand the problem.  (I think you crossed your 1/2 vs
> A/B/Y/Z in your example.) ...

It looks like I did, sorry about that.

> ... Clarifying the example above, if as you
> suggest an event happens in container Z, the hosts's auditd would report
>         Z,^2
> and the auditd in container 2 would report
>         Z,^2
> but if there were another auditd running in container Z it would report
>         Z
> while the auditd in container 1 or A/B would see nothing.

Yes.  My concern is how do we handle this to minimize duplicating and
rewriting the records?  It isn't so much about the format, although
the format is a side effect.

-- 
paul moore
www.paul-moore.com